MethodFirst you make filling for Dosa . Add oil in frying pan , make it hot then add mustard seedin it, when it splutter add curry eaves first then chopped onions, green chillies , potato ,turmeric powder and salt . Fry for2-3 min.Then add 1/2 cup of water and boil for 2-3 min. Keep aside this masala curry . Mix allingredients of batter add water to make a medium viscosity. ( After making this batter youcan store it for 3-4 days in fridge)Add oil in hot frying pan, add batter on it, spread over on frying pan in low flame . After 2min. put masala curry on the middle of dosa in horizontally. Fold dosa from two sides .Frydosa on both sides, add little oil ( If necessary ) .Serve hot with coconut chutney or without chutney .